08 DRR 50 L/C help

[redonkulousruntsracing]

Okay, I know I am an Apex guy, but one of the kids my boy races with has a 2 month old 08 DRR l/c 50 we need to get it going faster. His Dad (Dave) has been trying to do anything he can to make the 2 boys competetive. He has spent countless hours on the phone trying to find an answer and has been lead down the wrong road a few times. The DRR is bone stock and so is my Apex. I have mine dialed in to just about perfect now, but his DRR is not coming around like it should. Well, I shouldn't say the DRR is bone stock, the oil injection is gone, runs 110VP fuel, battery and electric start gone, UNI filter, carb jetted (still 16mm carb), 32 tooth rear sprocket, Red Malossi, 1000 rpm shoe springs, 3.75g rollers and the 782 belt Gary suggests. It runs great, starts right up, no problems except he isn't even close to my Apex. My son is 6-8 quad lengths out on the hole shot and a half lap lead on the first lap (supercross under the lights). We have tried letting the kids switch quads and we get the same results. I know there cant be that big of a difference in the 2 quads. Dave has been told by dealers that there are 2 different types of DRR you can get, a yard quad (which is kind of how his was when we got it, and one that is made for racing. A dealer at the last race let him ride a stock race ordered 50 and it was night and day to his. Is this so? There has to be something we can do to get the DRR so it will hang with the Apexs. I know "stock" DRR's won the National championships, so there must be something we can do.

Like I said, the clutching is there, it runs great, shifts in and out great, just low on power. It only has about 20When he has it on a stand and winds it out, you can hear the RPM's constantly rising, but it takes a while to get there, and it doesnt seem like it spins as many RPM's on top end and my kids Apex does. My Apex has a 19mm carb on it, and Dave thinks he needs a bigger carb, but I think his cylinder needs some work, thats my opinion, I have told him to stay with the 16mm carb, I dont think his motor flows enough to get a benefit of a bigger carb. I also think the stock pipe looks very restricted. Any thing else we could be missing? I learned on Apexs and this is Dave's first DRR so maybe we are missing something????????:confused: :confused:

[rmuscle]

i may be wrong but i think a stock apex out of the box is faster then a stock drr. i know some one will chime in if i am wrong but i think they come stock with a ported cylinder. also i know for a fact that some of the apex 50 come with a pipe that is similar to a drr 90 pipe , which makes a huge differance. we run against a girl that has one and everybody complains but because it comes stock on some apex 50s, so they consider it legal. i would nt switch the carb , we have a good amont of work done to our 50 and was running the 21 , gary told me to try the 16 and like it way better.the stock 50s winning at nationals i doubt are bone stock , im sure they have motor LEGAL motor work done to them.is the carb jetted correct , also may be dumb ? but did u he remove the clip on the cdi.also vp110 maybe to much octane for stock motor , cant burn it off fast enough , will slow u down.

[redonkulousruntsracing]

I know the Apex is factory ported and has a tuned pipe on it, but I know we can do some cylider porting on the DRR and still be legal, I think it just needs to breathe.
Clip on the CDI??? What would it do if it was still there? I haven't taken it off, but maybe Dave did when he gutted the electric start and oil injection.

[THARNESS]

All we did to Will's 50 in 2008 was port the cylinder. Everything else was stock and it ran pretty good.

A quality port job will do wonders for your friends DRR.

[rmuscle]

The clip will limit ur rpms I think

[bulldogfallon]

The cdi clip is gone or it would barely move


The CVT set up sounds rights


Your fuel is an issue.....all that octane is to much for that quad

Go back to 93 octane or a 100 octane mix....No need for that 110...


Get a tach so that it can be tuned without so much guesswork...

There is only 1 DRX50...no yard bike....never heard of that unless they were referring to the single a-arm version

Have you done a compression test and a leak down test?

If it is slow to rev it could be a leak issue....


I am curious to know if the exhaust port is small and D shaped or oval...there are 2 different LC cylinders...one is better stock and one is better for porting...

Get those numbers so we can have an intelligent CVT conversation

[bulldogfallon]

Also check the tranny gear ratio as well.....Some units had the high speed gears in them


Mark the bell and rotate to see how many times it takes to turn the sprocket once....

This would kill a 50....we had some come in like this.....

[don bassani]

Send cylinder to Hetrick,keep small carb,run less octane,fine tune clutch.This combo with good rider will win races.

[redonkulousruntsracing]

Thanks guys, I'll call Dave and let him know what you all had to say. Now we have some more things to check.

[redonkulousruntsracing]

Gary,
Can you tell me how many turns means high speed gears, and how many for low speed?? what are the ratios?

[bulldogfallon]

7 to 1 is high speed
9 to 1 is std ratio

[machwon]

Sickairseth, the clutch set up is wrong. Going by your ear or how good a motor revs can be very misleading sometimes. Of the half dozen 50's I've done they all use the following (except 09 models). Use a yellow malossi rear spring, 2000 rpm shoe springs, and 3 gram rollers for short tracks/holeshots, 3.5 gram rollers for the longer tracks, drop the 19 tooth front sprocket to an 18 and it should be much better. After that porting and a high compression head is all I would do to a 50 motor.

[bulldogfallon]

I am surprised that you can those springs to work with the light clutch that comes with the 50s nowadays..

The clutch would stall to almost 7K and that yellow spring is too weak to hold the belt in low gear...

I bet we get 95%+ holeshots each week against 12+ riders...

Our recomendation is:
Red Malossi
3.75 gram rollers
782 belt
Small Carb
Clutch engagement 6,200rpm

Stocker I would aim for 5,600 rpm

[machwon]

What would be wrong with the 7k engagement? I don't think it would read quite that high but tach's can really vary.

Is the belt he is using something other than stock?

[bulldogfallon]

Originally posted by sickairseth
There has to be something we can do to get the DRR so it will hang with the Apexs.


That's funny :)


We have one at our local series....not skeered at all...bring it :) :)

[bulldogfallon]

I think your statement is offbase...

We have used that set up (besides that clutch brand and shoe springs) and have had great success


To say that you have tried something else with success is different that saying that our recomendation is flat wrong.


7K engagement is too high for a quad that makes power in the high 8s to low 9s....plus the belt drops in the rear pulley before that rpm so the quad doesnt leave in low gear...maybe this is why you call for the 18t sprocket?

We run a 19x32 with 18" snow pigs.....

[bulldogfallon]

I have tested stock DRX50s with stock shoe springs and can find the clutch engagement at 6,500 at times....

The 2,000 shoe springs are stonger than stock as well..


The variator will also play a role in this....You can get a couple hundred rpm difference form the 2 different Yamasida DRR variators.


I think our results have prove that while you have had success with you set up (I didn't it was wrong) we have also experienced outstanding results with our approach to tuning which is also shared by another reputable shop we are close with.

Like I said....if your set up works for you great....I would just ask that you be more respectful when you say that our recomendation is wrong...as our results speak otherwise

[redonkulousruntsracing]

Originally posted by bulldogfallon
That's funny :)


We have one at our local series....not skeered at all...bring it :) :)


Gary, I was waiting for some one to chime in. LOL. My Apex was a turd when we got it, but after a lot of trial and error tuning, it rips!
I wasn't trying to be a smart a** either. Thanks for the help, looks like The DRR has the 7:1 gears in it, so I guess we will leave it like it is for the next couple of races then send the cylinder out to be ported. I dont know which one it has on it yet.

[bulldogfallon]

We always get the small D shaped exhaust cylinders since the other version is already very wide and can easily catch a ring with moire work.


Hetrick and Grissom seem to good work with the 50s.....


If you have the high speed gears that is killing that quad off the line.....

We changed those units to a 17 x 35 sprocket set up to combat those gears.

Take the gears out to be sure and count the teeth Should be 11/31 std or 13/28 high speed.

You may want to contact DRR since they are not an acceptable option with major sprocket changes

I would ask them for new gears-(exhcange) or 2 sprockets and a chain

That's is what I did for all of my customers with that issue

That is absolutely a MAJOR issue tight now....It like dropping 7 teeth on your rear sprocket...no way a stock 50 can overcome that.



On the DRR vs Apex...it poking for fun...It's the rider that wins the races.....not the sticker :)

[redonkulousruntsracing]

Gary, sorry , my bad. I meant it has the standard gears in it, 9:1, it's early and my brain hasn't started workin yet. All of you advice has been helpful. We will get it one way or the other.

And I agree, it's all rider. Last season there was a kid on modded DRR's that kept beating my son and Carson (the kid with the DRR). They both were on Arctic Cat/ Bomber 50's and we were like damn that kid is fast. This year with the boys on comparable equipment, it is showing that the fast kid from last year can't drive too good when there is competition. Our boys definitely look better out there now. I think a season of being the slower kids on sub-par machines tought them how to get the most out of what they had, they already knew how to push the limits, a new, fast quad just raised the bar for them!!